i965/fs: fix exec_size when emitting DIM instruction

Otherwise, DIM instructions will be emitted with the default exec size
which could be 16 in some cases, that is not legal.

Signed-off-by: Samuel Iglesias Gonsálvez <siglesias@igalia.com>
Suggested-by: Matt Turner <mattst88@gmail.com>
Reviewed-by: Matt Turner <mattst88@gmail.com>
diff --git a/src/mesa/drivers/dri/i965/brw_fs_nir.cpp b/src/mesa/drivers/dri/i965/brw_fs_nir.cpp
index 9f2729a..2ed843b 100644
--- a/src/mesa/drivers/dri/i965/brw_fs_nir.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs_nir.cpp
@@ -4813,7 +4813,7 @@
     * instruction allows to set the 64-bit immediate value.
     */
    if (devinfo->is_haswell) {
-      const fs_builder ubld = bld.exec_all();
+      const fs_builder ubld = bld.exec_all().group(1, 0);
       fs_reg dst = ubld.vgrf(BRW_REGISTER_TYPE_DF, 1);
       ubld.DIM(dst, brw_imm_df(v));
       return component(dst, 0);